Add distribution through `brew cask`

[klundberg]

I don't know how feasible this might be, but it would be nice to be able to just install a pre-built version of this app app through brew cask. That would require built releases to be stored on github or somewhere else at the very least, but it would be really convenient to not have to pull new code and rebuild it for every update.

How feasible do you think this might be?

[RobertGummesson]

I was thinking about that too and also to set up Travis to automatically build them.

I'm not sure how feasible this would be to be honest. I'm really an iOS developer and have no experience distributing OS X builds. I need to read up on it, particularly around the code signing.